Enhanced thermal shock resistance of low-carbon Al2O3-C refractories by aggregate/matrix interface design with MgAl2O4/CNTs layer

Abstract

Aggregate/matrix interface microstructure design to guide more cracks propagating within it favors improved thermal shock resistance of refractories. A MgAl2O4/CNTs interfacial layer was formed between the aggregate and matrix in low-carbon Al2O3-C refractories fabricated by core-shell corundum aggregates. The microstructural evolution of aggregate/matrix interface with increased contents of nickel nitrate hexahydrate catalyst in the interfacial layer and its effects on the thermal shock resistance of refractories were investigated. The results show that the highest amount of CNTs within the interfacial layer was obtained with the catalyst concentration of 0.5 wt%. The catalyst also promoted the growth of AlN whiskers that bridging the aggregate and matrix. Cracks impinging the interface are prone to be deflected by the interfacial layer and propagate within it. The deflection of cracks by the MgAl2O4 layer, the bridging and pulling out mechanism of the CNTS and AlN whiskers all contribute to the enhanced thermal shock resistance.